Heater core?

Tiny
DLOVE072257
  • MEMBER
  • 1998 CHEVROLET BLAZER
Is there a site out there that would show me diagrams on removing the heat/ventilation module from under the dash.
Monday, April 6th, 2009 AT 9:48 PM

74 Replies

Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS


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need manual CHECK IT @
https://www.2carpros.com/kpages/auto_repair_manuals.htm
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Thursday, December 27th, 2018 AT 8:18 PM
Tiny
OLWIG
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET BLAZER
  • 4.3L
  • V6
  • 4WD
  • AUTOMATIC
  • 58,000 MILES
Blower motor works, but I am not getting any heat. Heater core is not leaking and no smell. Temperature is reading good.
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
  • 1,853 POSTS
Once the engine warms up and the thermostat opens up feel both heater hoses going into the firewall, under the hood. The should now both be hot. If one is hot and the other cool or just warm then the heater core is clogged. If so, you could try back-flushing but if that does not knock loose the clog, then you will have to replace the heater core.
If both heater hoses are cool or just warm, see if there is a heater control valve located on either of those heater hoses, then if so, check the hose in front of and just after that valve and make sure they are both hot. If now, see if that valve vacuum hose fell off, etc, or if the valve is just stuck.
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 43,394 POSTS
Here is a guide that can help as well.

https://www.2carpros.com/articles/car-heater-not-working

Please let us know what happens.

Cheers, Ken
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
BDIXON
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET BLAZER
What do I have do to access and replace yhe heater core on this vehichle. :X
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
BRUCE HUNT
  • MECHANIC
  • 3,753 POSTS
The throwout bearing is what pushes against the fingers on the pressure plate and disengages the clutch to allow the shifting of the tranny. The bearing is failing but it still is doing its job. However, it is starting to grumble like an old man and replacement of the throwout is part of a clutch replacement. Replacing the clutch is very near for you.
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
MATHIASO
  • MECHANIC
  • 1,209 POSTS
Bruce Hunt is right.
You could have a clutch problems or internal transmission problems : neutral rollover rattle, damage input gear bearings misalignement of transmission with engine, worn or damage bearings. Check your fluid level first, it could be low. You could also have worn or brokken gears, excessive counter shaft end-play, or the main shaft gears are loose.
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
CHEVY22
  • MECHANIC
  • 1,375 POSTS
Well, patients, but the underside of the right dash below the glove box has to come off and the heater core removed from the inside, make sure to block hoses off before repair,
JIM
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
JERRYLMO
  • MEMBER
  • 27 POSTS
In your answer you mention the underside of the dash on the right side needs to come out. The shop manual says you have to pull the whole dash. I'm hoping that your alternate route is what it sounds like. I'd appreciate your advice.

By the way, my vehicle is a 2001 S10 4DR, 4WD Blazer and the heater core is leaking too.

Thanks for your time.
Jerry
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
CNASSEF
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 216,089 MILES
When I drive with the heater on it's only putting a small amount of wram air out if I have the RPM's up it;s warmer but when I idle it starts blowing out cold air how do I replace the heater core?
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
CHEVY22
  • MECHANIC
  • 1,375 POSTS
O1 is a little different, the whole dash does not have to come out per say, remove heater hoses and block off, remove speaker covers and center defroster grill you will find a bunch of phillips head screws along the op remove all but two, remove all lower dash covers, and there are six main bolts that do not have to come out but losse, if you look hard you will see which ones would make the dash fall toward the seat, then remove two top scews you left in, dash will fall back and you have a few more screws on the core cover, book calls for 1o hrs ive done them in six but I break it up into two days so your not stuck under there all day
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
You might try a good radiator flush and then taking a hose and back flushing the heater core before going the trouble of replacing the core, especially if it's not leaking. You have to pull the dash out to get he heater core out on that model. Of course check to make sure that you have afull coolant as that will effect your heat if it is low. If itis then have your engine pressure checked as you may have a bad intake or head gasket.
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
JERRYLMO
  • MEMBER
  • 27 POSTS
As you can see by the pictures I got the dash to lean out and I took out all the screws of the A/C module box but it's not coming apart. If I lift up on the top of the case it gaps open but it appears it's still connected together. To go further It looks like the dash is actually going to have to come out. This appears to require letting the steering column down, unplugging several major electrical connections and getting into the Air Bag controls. That's really my biggest concern, after all this I'd hate to fire off the air bags and add that to the job.
Any help is appreciated!

Thank you,
Jerry


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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
CHEVY22
  • MECHANIC
  • 1,375 POSTS
Go under the hood ontop of the evap core, and there sits the blower motor resistor, there are three bolts, you will not be able to see them but there is a cutting guide on the housing to cut the plastic to reveal the bolts 5.5mm once the resister is pulled look down into the box and you will see one 10mm bolt that needs to come out , also there are two under, one is behind the right exhasut manifold and the other is same height but closer to the right wheel, these two go to studs on the lower right corner of the ac module and one right next to the heater hoses and its out, sorry about that I thought you meant just the dash, warning the one behind rhe exhaust manifold is tricky 10mm one turn at a time, and if you do want more room you can drop the column should be 4 retainers 10mm and two column boilts 15 mm but I alway snuck em out without it, its tougher but savers about 20 minutes in the round trip, oh and I never unplug anything I always more a harness from a clip if needed, no sense in pulling what you dont need, as long as the battery is disconnected the air bags will be ok, remember all you need to do is to pull the module out enough to clear the heat core lines on the inside of the firewall to remove the two top cover bolts, thats why I never go too far
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
JERRYLMO
  • MEMBER
  • 27 POSTS
I was able to locate and remove all the fasteners you told me about and I even found one extra. However, the whole box wiggles but isn't coming away from the firewall. Does it have anything to do with air distribution vents on the bottom of the box for heating? They seem to be separate but I'm wondering if they're in the way. I'm so close to getting the core out and this one last thing is holding up the show. I haven't given up though.
Thanks for your time.
Jerry
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
TONI LICHTMAN BURNS
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET BLAZER
  • 4.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 260,000 MILES
My SUV does not get heat. Air conditioner works fine, replaced radiator, heater core, thermostat, purged all air out, actuator seems to work, it just does not get heat.
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
CHEVY22
  • MECHANIC
  • 1,375 POSTS
As long as you have the tree plus the one one the firewall at the heater core lines you should be good, the two on the lower firewall are studsthey may be holding you up and as long as you pulled theresistor out and got that one give it a yank
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,758 POSTS
With the engine at full operating temperature, locate the two heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If they are both hot, the heat in that vehicle is controlled by a blend door that regulates heated air flow. It is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
JERRYLMO
  • MEMBER
  • 27 POSTS
Indeed there were the fasteners you told me about but there was one more WELL HIDDEN lag bolt looking thing that went in from the firewall and fastened the outside Evap cover going all the way through into the A/C box. It took me an hour to find it but it's right by the passenger side valve cover on the fire wall. It took a 24" 3/8 drive extension and a 10mm universal socket to get to it and that was pretty tight. Once I took it out the whole box popped right out and I'm about to remove that * &%&*@## heater core. Now if I can just remember how it all goes back to gether. :Mrgreen:
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)
Tiny
JERRYLMO
  • MEMBER
  • 27 POSTS
Many thanks for all your help. I'd still be pulling my hair out trying to figure this out without it.
Jerry
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Wednesday, August 19th, 2020 AT 8:21 PM (Merged)

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